Financial Instruments Carried at Fair Value on Recurring Basis (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Contracts	$ 24,800,000	$ 20,500,000
Total, Assets	68,200,000	20,500,000
Derivatives, Liabilities	8,500,000	1,700,000
Contingent consideration arising from acquisitions, liabilities	13,300,000	17,500,000
Total, Liabilities	21,800,000	19,200,000
Fixed Maturity Mutual Funds and Open Ended Mutual Funds	43,400,000
Fair Value Inputs Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Contracts	24,800,000	20,500,000
Total, Assets	24,800,000	20,500,000
Derivatives, Liabilities	8,500,000	1,700,000
Contingent consideration arising from acquisitions, liabilities	0	0
Total, Liabilities	8,500,000	1,700,000
Fixed Maturity Mutual Funds and Open Ended Mutual Funds	0
Fair Value Inputs Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Contracts
Total, Assets
Derivatives, Liabilities	0	0
Contingent consideration arising from acquisitions, liabilities	13,300,000	17,500,000
Total, Liabilities	13,300,000	17,500,000
Fixed Maturity Mutual Funds and Open Ended Mutual Funds	0
Fair Value Inputs Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Contracts
Total, Assets	43,400,000
Derivatives, Liabilities	0	0
Contingent consideration arising from acquisitions, liabilities	0	0
Total, Liabilities
Fixed Maturity Mutual Funds and Open Ended Mutual Funds	$ 43,400,000